JPH09148508A - Lead frame for semiconductor device and plastic molded type semiconductor device using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lead frame for a semiconductor device whose reliability like moisture resistance or thermal shock resistance is sufficiently improved and which is suitably used for a plastic molded type semiconductor device. SOLUTION: Electrolytic treatment is performed on the whole surface of a lead frame, in electrolytic solution containing at least one kind of metal ion selected out of Cu, Zn and Ni, by using current density exceeding the limiting current density. A roughened layer constituted of protruding type electrodeposition having a needle shape or a branch shape obtained by the above treatment, and a covering layer constituted of smooth electrodeposition which is obtained by performing electrolytic treatment, in electrolytic solution containing at least one kind of metal ion selected out of Cu, Zn, Ni, In, Mo, Co and Cr, by using current density smaller than or equal to the limiting current density are formed in order.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device lead frame and a resin-sealed semiconductor device using the same.

[0002]

2. Description of the Related Art A resin-encapsulated semiconductor device is manufactured by placing a lead frame formed by mounting and wiring semiconductor elements on a mold, and then encapsulating the resin to separate the mold from the molded product. It is essential to add a releasing agent such as higher fatty acid or higher fatty acid salt to the resin in order to improve the properties.

However, this release agent reduces the adhesion between the lead frame and the resin, and causes the moisture resistance of the resin-sealed semiconductor device to be impaired.

Japanese Unexamined Patent Publication (Kokai) No. 1-171257 describes that a roughening layer is provided on the surface of the lead frame main body by electrolytic treatment in order to improve the adhesion between the resin and the lead frame. This roughening layer is provided by using the metal of the lead frame as a cathode and performing electrolysis in an electrolytic solution containing metal ions at a current density near or above the limiting current density. This roughening layer is caused by the electrodeposited electrodeposits on the surface of the electrodeposited needle-like or dendritic electrodeposited metal, but the electrodeposited protrusions formed at current densities above the critical current density are The resin-encapsulated semiconductor device is fragile, cannot sufficiently improve the adhesiveness, and cannot sufficiently satisfy the moisture resistance.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of such circumstances, and a resin-sealed semiconductor device having sufficiently improved reliability such as humidity resistance or thermal shock resistance, and a semiconductor device preferably used for the same. To provide a lead frame for use.

[0006]

Means for Solving the Problems As a result of intensive studies for achieving the above-mentioned object, the inventors of the present invention produced a lead frame having a specific roughening layer and a coating layer sequentially provided on the entire surface. It was found that the resin-encapsulated semiconductor device has excellent reliability such as moisture resistance and thermal shock resistance, and the present invention has been completed based on this finding.

That is, in the present invention, at least one selected from Cu, Zn and Ni is provided on the entire surface of the lead frame body.
Roughening layer composed of needle-like or dendritic protrusion-like electrodeposits obtained by electrolytic treatment at a current density exceeding a limiting current density in an electrolyte solution containing certain metal ions, Cu, Zn, Ni, I
A coating layer composed of a smooth electrodeposit obtained by electrolytic treatment at a current density of a limiting current density or less in an electrolytic solution containing at least one metal ion selected from n, Mo, Co and Cr, and optionally silane. The present invention provides a lead frame for a semiconductor device in which an adhesive layer made of a coupling agent is sequentially provided.

The present invention also provides a resin-encapsulated semiconductor device in which a lead frame for a semiconductor device obtained by mounting and wiring a semiconductor element as described above is placed in a mold and then resin-sealed. It is provided.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION In the lead frame of the present invention, a roughening layer, a coating layer, and
An adhesive layer is sequentially provided as needed. The material of the lead frame body is not particularly limited, but examples thereof include copper-based materials such as oxygen-free copper, phosphor bronze, tin-filled copper, and iron-filled copper, iron-nickel-based alloys, molybdenum-based or tungsten-based metal materials. .

These lead frame bodies are untreated, preliminarily subjected to alkali degreasing and acid cleaning, mechanically roughened with sandpaper, wire brush, honing, etc., or electrolytic oxidation in an electrolytic solution. Alternatively, it may be chemically roughened in an acid / alkali solution. Further, the surface may be plated with copper strike.

The roughening layer formed on the entire surface of the lead frame uses the metal of the lead frame as the cathode, and the anode is made of lead, lead alloy, platinum, iridium, or the like.
It is composed of a needle-like or dendritic protrusion-shaped electrodeposit obtained by electrolytic treatment at an electric current density exceeding a limiting current density in an electrolytic solution containing at least one metal ion selected from n and Ni, and has a rough surface. Although it is surfaced and the adhesion with the resin is improved by the anchoring effect, the roughened layer is brittle and sufficient adhesion cannot be obtained.

Therefore, in the present invention, a coating layer for compensating the brittleness of the roughened layer is further provided on the roughened layer. This coating layer is a smooth electrodeposit obtained by electrolytic treatment at a current density of a limiting current density or less in an electrolytic solution containing at least one metal ion selected from Cu, Zn, Ni, In, Mo, Co and Cr. The needle-like or dendritic protrusion-shaped electrodeposit of the roughened layer is covered with the layer consisting of. If the thickness of this layer becomes too thick, the rough surface due to the protruding electrodeposit will be lost.
0.01-2 μm so as not to damage the unevenness of the protruding electrodeposit
The thickness is preferably

The coating layer may be formed at once, or may be divided into two portions by using two or more kinds of electrolytic solutions. The first coating layer can be formed by directly using the electrolytic solution used for forming the roughened layer. The uppermost layer of the coating layer is preferably a layer having rust resistance, heat resistance, and moisture resistance.

The electrolysis conditions for forming the roughening layer and the coating layer are appropriately determined according to the composition of the plating bath, but the formation of the roughening layer exceeds the limiting current density in the electrolytic solution containing metal ions. It is done at current density. The current density is preferably 1 to 150 A / dm ² higher than the limiting current density. Further, the coating layer is formed in an electrolytic solution containing metal ions at a current density not higher than the limiting current density. The current density is preferably 5 to 95% smaller than the limiting current density.

Regarding the conditions for forming the roughened layer, specifically,
For example, in the case of copper, copper sulfate 10 to 150 g / l, sulfuric acid 10
~ 150 g / l, glue 0.1-2 g / l electrolyte solution,
pH 1 or less, temperature 10 to 50 ° C, cathode current density 10 to 1
Treatment is performed under the conditions of 50 A / dm ² and electrolysis time of 1 to 60 seconds. In the case of nickel, nickel sulfate 10-150 g /
1, ammonium acetate 10-50 g / l, boric acid 10-50 g
/ L, sodium sulfate 50-150 g / l of electrolytic solution, pH 4-6, temperature 20-60 ° C, cathode current density 10
Treatment is performed under the conditions of ˜80 A / dm ² and electrolysis time of 1-60 seconds. In the case of zinc, zinc sulfate 10-200 g / l, sulfuric acid 1
~ 5 g / l, aluminum sulphate 1-5 g / l, dextrin 1-5 g / l electrolyte solution, pH 5-6, temperature 1
Treatment is carried out under conditions of 0 to 50 ° C., cathode current density of 5 to 100 A / dm ² , and electrolysis time of 1 to 60 seconds.

Regarding the conditions for forming the coating layer, specifically,
For example, in the case of copper, copper sulfate 10 to 400 g / l, sulfuric acid 10
~ 150 g / l electrolyte, pH 1 or less, temperature 10
The treatment is carried out under the conditions of -50 ° C, cathode current density of 0.1-10 A / dm ² , and electrolysis time of 1-180 seconds.

In the case of nickel, nickel sulfate 10 to 45
0 g / l, ammonium acetate 10-50 g / l, boric acid 10-
Treatment is carried out using an electrolytic solution of 50 g / l and 50-150 g / l of sodium sulfate under the conditions of pH 4-6, temperature 20-75 ° C., cathode current density 0.1-5 A / dm ² , and electrolysis time 1-180 seconds. . In the case of zinc, zinc sulfate 10-300 g /
1, sulfuric acid 1-5 g / l, aluminum sulfate 1-50 g /
1 and dextrin 1 to 5 g / l of electrolyte solution, pH 5
~ 6, temperature 10 ~ 60 ° C, cathode current density 0.1 ~ 5A /
It is processed under the conditions of dm ² and electrolysis time of 1 to 180 seconds.

In the present invention, if necessary, an adhesive layer made of a silane coupling agent is provided on the coating layer, and by providing this adhesive layer, the adhesiveness with the resin is further improved. This adhesive layer is formed by immersing the lead frame main body provided with the roughening layer and the coating layer in a 0.001 to 5% by weight aqueous solution of a silane coupling agent and drying the same. The thickness of the adhesive layer is preferably 0.01 to 1 μm. The adhesive layer crosslinks the surface of the coating layer made of an electrodeposit such as metal, metal oxide, and metal hydroxide with the resin to improve the adhesiveness.

Examples of the silane coupling agent used for forming the adhesive layer include 3-glycidoxypropyltrimethoxysilane, epoxy silane such as 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, and 3-aminopropyltrimethoxysilane. Examples thereof include aminosilanes such as ethoxysilane, and mercaptosilanes such as 3-mercaptopropyltrimethoxysilane, but are not limited thereto.

A semiconductor element is mounted and wired on the lead frame for a semiconductor device on which the roughening layer, the coating layer, and the adhesive layer obtained in the above-described order are provided. If the resin is encapsulated with, a desired resin-encapsulated semiconductor device having excellent moisture resistance and thermal shock resistance can be obtained.

When mounting and wiring the semiconductor element, it is preferable to remove the surface treatment layer at a necessary place for plating by chemical etching using a cupric chloride solution or the like.

[0022]

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to Examples of the present invention and Comparative Examples thereof, but the present invention is not limited to these Examples.

Example 1 Copper alloy lead frame material (MF manufactured by Mitsubishi Electric Corp.)
After the surface of 202) was pickled with 5 wt% sulfuric acid and washed with water, a roughening layer, a covering layer, and an adhesive layer were sequentially formed on the surface of the lead frame using the following procedure.

(1) Formation of Roughening Layer Plating bath composition: copper sulfate pentahydrate 100 g / l, sulfuric acid 1
In a plating bath of 00 g / l, bath temperature: 30 ° C., pH: 0.3, cathodic current density: 15 A / dm ² , electrolysis time: 3 seconds, electroplating was performed under electrolysis conditions exceeding the limiting current density, and leads were obtained. A roughened dendritic layer was formed on the surface of the frame.

(2) Formation of coating layer Following formation of the roughening layer, electroplating (cathode current density: 3 A / dm ² ; electrolysis time: 60 seconds) under electrolysis conditions below the limiting current density in the same plating bath. The previous step) was performed to form a copper coating layer so that the dendritic copper roughened layer became granular, and then washed with water.

Next, plating bath composition: zinc sulfate heptahydrate 200 g / l, ammonium chloride 5 g / l, aluminum sulfate 30 g / l, bath temperature: 30 ° C., pH: 5 in the plating bath, cathode current density : 0.5 A / dm ² , electrolysis time:
Electroplating (second stage) was performed under electrolysis conditions of 3 seconds or less of the limiting current density to form a smooth zinc coating layer on the granular copper coating layer, followed by washing with water.

(3) Formation of Adhesive Layer After immersing the lead frame having the roughening layer and the coating layer in a 0.1% by weight aqueous solution of silane coupling agent (3-glycidoxytrimethoxysilane) for 20 seconds. ,
It was dried for 5 minutes in a dryer maintained at a temperature of 100 ° C to form an adhesive layer.

Next, a resist film (HF-24 manufactured by Hitachi Chemical Co., Ltd.) is formed on the surface of the surface-treated lead frame.
0) was coated, exposed and developed, and the surface-treated layer at the plating-needed portion (inner lead portion, die pad portion) was removed by etching with a cupric chloride solution.

Next, silver plating (spot plating) is applied to the plating-required portions that have been removed by etching, and a semiconductor element (DIP type 16 pin, chip size: 4 × 7 mm) is bonded and mounted on the die pad portion using silver paste. The lead and the semiconductor element electrode portion were connected with a gold wire.

Further, the semiconductor element mounted on the lead frame except for the outer leads is resin-sealed with an epoxy resin sealant (CEL-9000 manufactured by Hitachi Chemical Co., Ltd.) to obtain a resin-sealed semiconductor device. Obtained.

The resin-encapsulated semiconductor device was subjected to the following tests and evaluated. Table 1 shows the evaluation results.

Moisture resistance test 40 resin-encapsulated semiconductor devices each were manufactured and 260
After dipping in a solder bath for 20 seconds, 121 ℃, 2at
Under a condition of m and 100% RH, a moisture resistance test (PCT test) after immersion in a solder bath was performed (1500 hr), and the moisture resistance was evaluated from the defective occurrence rate of package cracks at that time.
◯ indicates a defect occurrence rate of 5% or less, and x indicates a defect occurrence rate of 90% or more.

Thermal shock resistance test 40 resin-sealed semiconductor devices each were manufactured. This is 15
Immediately after immersing in a 0 ° C silicone oil bath for 2 minutes, -19
A thermal shock test was conducted with one cycle consisting of a thermal cycle in which liquid nitrogen at 6 ° C. was rapidly cooled for 2 minutes (2000 cycles), and the thermal shock resistance was evaluated from the defective occurrence rate of package cracks at that time. ◯ indicates a defect occurrence rate of 5% or less, and x indicates a defect occurrence rate of 90% or more.

Example 2 A lead frame and a resin-sealed semiconductor device were obtained in the same manner as in Example 1 except that the roughening layer and the coating layer were formed as follows. Table 1 shows the evaluation results.

(1) Formation of roughening layer Plating bath composition: copper pyrophosphate 100 g / l, potassium pyrophosphate 300 g / l, ammonia water 2 ml / l, bath temperature: 25 ° C., pH: 8.5 in plating bath Then, electroplating was performed under electrolysis conditions in which the cathode current density was 6 A / dm ² and the electrolysis time was 6 seconds, which exceeded the limiting current density, and a needle-like roughened copper layer was formed on the surface of the lead frame, followed by washing with water.

(2) Formation of coating layer Composition of plating bath: copper sulfate-5 hydrate 20 g / l, zinc sulfate heptahydrate 8 g / l, sodium glucoheptonate 50
g / l, potassium thiocyanate 5 g / l, potassium oxalate 30 g / l, bath temperature: 40 ° C., pH: 11 in a plating bath, cathode current density: 5 A / dm ² , electrolysis time: limiting current of 15 seconds The lead frame on which the roughened layer was formed was electroplated under electrolytic conditions of density or less, a smooth copper-zinc coating layer was formed on the roughened layer, and washed with water.

Example 3 A roughening layer and a coating layer were formed in the following manner, and an adhesive layer was formed using 3-aminopropyltriethoxysilane of 0.
A surface-treated lead frame and a resin-encapsulated semiconductor device were obtained in the same manner as in Example 1 except that the 1 wt% solution was used. Table 1 shows the evaluation results.

(1) Formation of Roughening Layer Plating bath composition: copper sulfate pentahydrate 30 g / l, nickel sulfate hexahydrate 70 g / l, bath temperature: 25 ° C., pH: 2.
0 in plating bath, cathode current density: 3.5 A / dm ² ,
Electrolysis time: Electroplating was performed under electrolysis conditions exceeding the limiting current density of 8 seconds to form a needle-like roughened copper-nickel layer on the surface of the lead frame and washing with water.

(2) Formation of coating layer Plating bath composition: sodium dichromate 3.5 g / l, bath temperature: 25 ° C., pH: 5.5 in the plating bath, cathode current density: 0.5 A / dm ^2. Electrolysis time: electroplating was performed on the lead frame on which the roughened layer was formed under the electrolytic condition of the limiting current density of 5 seconds or less, a smooth chromate coating layer was formed on the roughened layer, and washed with water. .

Example 4 A surface-treated lead frame and a resin-sealed semiconductor device were obtained in the same manner as in Example 1 except that the roughening layer and the coating layer were formed as follows. Table 1 shows the evaluation results.

(1) Formation of roughening layer Plating bath composition: zinc sulfate hexahydrate 200 g / l, ammonium chloride 5 g / l, aluminum sulfate 30 g / l,
Electroplating was performed in a plating bath having a bath temperature of 25 ° C. and a pH of 5 to 6 with a cathode current density of 5 A / dm ² and an electrolysis time of 3 seconds, and electroplating was performed to obtain a needle-shaped rough copper wire. A chemical layer was formed and washed with water.

(2) Formation of coating layer Plating bath composition: zinc sulfate hexahydrate 5 g / l, sodium dichromate dihydrate 5 g / l, bath temperature: 30 ° C., p
Cathode current density: 0.5 A / dm in H: 5 plating bath
^2. Electrolysis time: electroplating the lead frame on which the roughened layer is formed under the electrolysis condition of the limit current density of 5 seconds or less,
A smooth chromium-zinc coating layer was formed on the roughened layer and washed with water.

Example 5 A lead frame material made of an iron-42% nickel alloy was used, a roughening layer and a coating layer were formed as follows, and an adhesive layer was formed by 2- (3,4-). A surface-treated lead frame and a resin-sealed semiconductor device were obtained in the same manner as in Example 1 except that a 0.3 wt% solution of epoxycyclohexyl) ethyltrimethoxysilane was used. Table 1 shows the evaluation results. Before forming the roughened layer, the plating bath composition: copper pyrophosphate trihydrate 150 g / l, potassium pyrophosphate 400 g / l, bath temperature: 40 ° C., pH:
In the plating bath of No. 9, copper strike plating with a cathode current density of 2 A / dm ² and an electrolysis time of 30 seconds was carried out, followed by washing with water.

(1) Formation of Roughening Layer Plating bath composition: nickel sulfate 70 g / l, sodium sulfate 150 g / l, ammonium acetate 50 g / l, boric acid 1
Copper strike plating is performed in a plating bath of 5 g / l, bath temperature: 30 ° C., pH: 6 under the electrolytic conditions exceeding the limiting current density of cathode current density: 12 A / dm ² and electrolysis time: 60 seconds. A needle-like roughened nickel layer was formed on the surface of the lead frame subjected to the treatment.

(2) Formation of coating layer Subsequent to formation of the roughening layer, electroplating (cathode current density: 2 A / dm ² ; electrolysis time: 60 seconds) in the same plating bath under electrolysis conditions below the limiting current density. The previous step) was performed to form a nickel coating layer so that the needle-shaped roughened nickel layer was in a granular form, followed by washing with water.

Next, plating bath composition: indium sulfate 2
g / l, zinc sulfate 2 g / l, bath temperature: 30 ° C., pH: 3 in a plating bath, cathode current density: 0.5 A / dm ² , electrolysis time: 5 seconds Electroplating (second stage) was performed to form a smooth indium-zinc coating layer on the nickel coating layer, followed by washing with water.

Example 6 The formation of the roughening layer and the subsequent formation of the coating layer (formation of the granular copper coating layer) were performed in the same manner as in Example 1, and the formation of the coating layer of Example 5 was performed after the formation of the coating layer, that is, Except that the formation of the indium-zinc coating layer was changed to the formation of the nickel-molybdenum-cobalt coating layer shown below and the formation of the adhesive layer was performed using a 0.3 wt% solution of 3-mercaptopropyltrimethoxysilane. A surface-treated lead frame and a resin-sealed semiconductor device were obtained in the same manner as in Example 5. Table 1 shows the evaluation results.

(2) Formation of coating layer Plating bath composition: Nickel sulfate hexahydrate 30 g / l, sodium molybdate dihydrate 5 g / l, cobalt sulfate heptahydrate 7 g / l, citric acid Trisodium dihydrate 30g / l, bath temperature: 30 ° C, pH: 6 in a plating bath, cathode current density: 2A / dm ² , electrolysis time: 10 seconds, electrolysis under electrolysis conditions below the limiting current density Plating (latter stage 1) was carried out to form a smooth nickel-molybdenum-cobalt coating layer on the roughened layer, followed by washing with water.

Next, in the plating bath composition: sodium dichromate 3.5 g / l, bath temperature: 25 ° C., pH: 5.5, cathode current density: 0.5 A / dm ² , electrolysis time: Electroplating (latter stage 2) was performed under electrolysis conditions of 5 seconds or less of the limiting current density to form a smooth chromate coating layer on the nickel-molybdenum-cobalt coating layer and washing with water.

Example 7 A lead frame surface-treated in the same manner as in Example 1 except that the coating layer was changed to the nickel-phosphorus layer formed as follows and no adhesive layer was provided. A resin-sealed semiconductor device was obtained. Table 1 shows the evaluation results.

(2) Formation of coating layer Plating bath composition: nickel sulfate hexahydrate 35 g / l, nickel chloride hexahydrate 10 g / l, nickel carbonate 5 g / l
1, phosphoric acid 12 g / l, phosphorous acid 7 g / l, bath temperature: 50
Cathode current density: 1A in a plating bath at ℃, pH: 1.5
/ Dm ² , electrolysis time: electroplating is performed on the lead frame on which the roughened layer is formed under electrolysis conditions of a limiting current density of 30 seconds or less, a smooth nickel-phosphorus coating layer is formed on the roughened layer, and the surface is washed with water. I went.

Example 8 The pre-stage (formation of a granular nickel coating layer) for forming a roughening layer and a coating layer was carried out in the same manner as in Example 5, and the In-Zn layer was formed after the coating layer formation. A lead frame surface-treated in the same manner as in Example 1 except that the copper-zinc layer was formed in the same manner as in Example 2 except that no adhesive layer was provided.
A resin-sealed semiconductor device was obtained. Table 1 shows the evaluation results.

Comparative Example 1 A surface-treated lead frame having only a copper roughening layer and a resin-sealed semiconductor device were obtained in the same manner as in Example 1 except that the coating layer and the adhesive layer were not formed. It was Table 1 shows the evaluation results.

Comparative Example 2 Only a zinc coating layer was formed in the same manner as in Example 1 except that the roughening layer was not formed, the coating layer was not formed in advance (the granular copper coating layer was formed), and the adhesive layer was not formed. A surface-treated lead frame and a resin-sealed semiconductor device were obtained. Table 1 shows the evaluation results.

Comparative Example 3 A surface-treated lead frame having only an adhesive layer and a resin-sealed semiconductor device were obtained in the same manner as in Example 3 except that the roughening layer and the coating layer were not formed. Table 1 shows the evaluation results.
Shown in

[0056]

[Table 1]

[0057]

The resin-encapsulated semiconductor device manufactured by using the lead frame for a semiconductor device of the present invention is excellent in moisture resistance and thermal shock resistance, and its industrial value is extremely large.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Takeshi Yamagishi 1226 Shimoeren, Shimodate-shi, Ibaraki Japan Electrolysis Company Shimodate factory

Claims (3)

[Claims] 1. Cu, Z on the entire surface of the lead frame body.
A roughened layer made of a needle-like or dendritic projection-like electrodeposit obtained by electrolytic treatment at a current density exceeding a limiting current density in an electrolytic solution containing at least one metal ion selected from n and Ni, Cu, A coating layer composed of a smooth electrodeposit obtained by electrolytic treatment at a current density of a limiting current density or less in an electrolytic solution containing at least one metal ion selected from Zn, Ni, In, Mo, Co and Cr is sequentially formed. A lead frame for a semiconductor device provided. 2. The entire surface of the lead frame body is Cu, Z
A roughened layer made of a needle-like or dendritic projection-like electrodeposit obtained by electrolytic treatment at a current density exceeding a limiting current density in an electrolytic solution containing at least one metal ion selected from n and Ni, Cu, A coating layer composed of a smooth electrodeposit obtained by electrolytic treatment at a current density not higher than the limiting current density in an electrolytic solution containing at least one metal ion selected from Zn, Ni, In, Mo, Co and Cr, and silane. A lead frame for a semiconductor device, in which an adhesive layer made of a coupling agent is sequentially provided. 3. A resin-encapsulated semiconductor device, comprising: mounting and wiring a semiconductor element; and arranging the semiconductor device lead frame according to claim 1 in a mold, and then encapsulating with a resin.